Drill mine

ABSTRACT

A drill mine, having the same operational and physical characteristics as a service mine is provided with apparatus for indicating mine actuation and for providing retrieval thereof. A buoyant float assembly is provided which shortly after water entry separates from the drill mine body but remains tethered thereto. Upon mine actuation a smoke generating signal float is released from the float assembly and rises to the surface thereby giving an indication of mine actuation. After a preset time, the float assembly is released from its tethered mode and floats to the surface carrying a recovery line therewith. Upon surfacing, recovery personnel may use the recovery line to remove a heavy retrieval line stored and fixed within the mine case. The retrieval line is employed to pull the mine from the bottom onto a recovery vessel.

Unite States Patent 1191 Costley et a1.

[ 1 Jan. 9, 1973 54] DRILL MINE Inventors: vivian fif fiostley,kensington iiigfitsjfiaffs' ivih Wolf, Silver Spring, Md.

[73] Assignee: The United States of America as represented by theSecretary of the Navy 22 P111511? A hirl 1113571 [21] Appl. No.: 130,141

[52] U.S. Cl. ..l02/10, 102/13 [51] Int. Cl ..F42b 22/00 [58] Field ofSearch ..102/10,l3,14

[56] References Cited UNITED STATES PATENTS 2,775,939 1/1957 Fogal..l02/13 2,813,486 11/1957 Goth... 2,949,853 8/1960 Vogt..... 3,017,8311/1962 Barry 4/1963 Butler et al ....102/l0 Primary Examiner-Samuel W.Engle Attorney-R. S. Sciascia, J. A. Cooke, R. J. Erickson and M. G.Raskin [57] ABSTRACT A drill mine, having the same operational andphysical characteristics as a service mine is provided with apparatusfor indicating mine actuation and for providing retrieval thereof. Abuoyant float assembly is provided which shortly after water entryseparates from the drill mine body but remains tethered thereto.

Upon mine actuation a smoke generating signal float is released from thefloat assembly and rises to the surface thereby giving an indication ofmine actuation. After a preset time, the float assembly is released fromits tethered mode and floats to the surface carrying a recovery linetherewith. Upon surfacing, recovery personnel may use the recovery lineto remove a heavy retrieval line stored and fixed within the mine case.The retrieval line is employed to pull the mine from the bottom onto arecovery vessel.

5 Claims, 5 Drawing Figures- PAIENTEfim '9 m3 3.709.148

INVENTORS Vivian G. Costley ylvan Wolf BY 7 iZwfl/ ATTORNEY HQJZMCT 405mDRILL MINE BACKGROUND OF THE INVENTION This invention relates generallyto drill mine apparatus and more particularly to a realisticallyconfigured drill mine which provides a visual signal indicative of mineactuation and further provides for retrieval of the drill mine.

In the past, drill mines have been used in orderto provide operationaltraining devices for personnel who normally would operate the actualservice mine counterparts. In previous air launched bottom drill mines,an extension section was provided between the tail of the mine case andthe disposable flight gear to house the mine actuation signal andrecovery equipment. The

rn ine case explosive compartment is usually filledwith inert material.The extension section with the signal and recovery equipment appreciablychanged the length, weight and center of gravity of the mine. It furtheraltered its handling and loading characteristics aboard the launchingaircraft and often decreased the number of drill mines that could becarried relative to service mines. Further, the changed physicalcharacteristics caused the maximum planting speed, the ballisticcharacteristics and the underwater trajectory to differ from the servicemine. Other problems inherent in drill mines having extended drillsections provided at the ends thereof include necessitating the use of adifferent type of parachute pack and release mechanism and fairing thanemployed on the service mine. All of these changes affect the realism ofthe drill mines thereby greatly reducing their training value.

The mine actuation signal mentioned hereinabove indicates when the drillmine is actuated during tests and usually take the form of buoyant smokeand flame producing float devices releasably connected to the mine case.Upon actuation of the mine by the passage of a target ship or the like,these float devices may be released thereby rising to the surface toprovide a visual indication of mine actuation. The conventional drillmines as described hereinabove create a number of difficulties, however.It has not been uncommon for a test mine upon reaching the floor of thebody of water to become buried in the soft, muddy surface thereof. Whenthis occurred, frequently, the float was prevented from releasing itselffrom the mine body due to the muddy environment. In these cases, for allintents and purposes, the mine served no further use. Still anotherproblem was inherent in the prior recovery procedures used in drill mineoperations. In the past, divers were necessarily employed in order toaccomplish retrieval of the mine, often entailing a great expenditure oftime between test runs.

SUMMARY OF THE INVENTION Accordingly, one object of this invention is toprovide a new and improved drill mine having the same physical andoperational characteristics as its service mine counterpart.

Another object of the invention is the provision of a new and improveddrill mine including apparatus for providing visual signals indicativeof mine actuation.

A further object of the instant invention is to provide a new andimproved float assembly which separates from the drill mine prior to themine settling on the bottom of the body of water.

A still further object of this invention is the provision of a new andimproved system for facilitating and effecting retrieval of the drillmine from a surface ship without the use of divers.

Briefly, in accordance with one embodiment of this invention, these andother objects are attained by providing in a portion of a drill minehaving an identical configuration to its service mine counterpart, apositively buoyant float assembly adapted to be expelled from the drillmine shortly after water entry. The float assembly is tethered to thedrill mine and remains suspended a relatively short distance thereaboveas the mine descends and finally settles to the bottom of the sea. Thefloat assembly is provided with a buoyant signal float and a primaryrecovery line. The primary "recovery line is connected at its end to arecovery cable stored in another part of the drill mine body. Upon mineactuation, the signal float is expelled from the float assembly andrises, entirely free from the drill mine body, to the surface wheresuitable visual displays are caused to occur, thereby indicating theactuation of the mine. The tethering line connecting the float assemblyto the drill mine is caused to be severed by one ofa number of possiblemethods such, for example, as a timer actuated cutting device. The floatassembly then rises to the surface paying out the primary recovery linestored therein. Upon reaching the surface, personnel on the recoveryship may, by grasping and withdrawing the primary recovery line, therebyextricate the recovery cable. The recovery cable is of sufficientstrength to enable the drill mine to be lifted from the bottom.

BRIEF DESCRIPTION OF THE DRAWING A more complete appreciation of theinvention and many of the attendant advantages thereof will be readilyappreciated as the same becomes better understood by reference to thefollowing detailed description when considered in connection with theaccompanying drawings wherein:

FIG. 1 is a side elevation view in partial section of the drill mineaccording to the present invention;

FIG. 2 is a plan view taken along line 2-2 of FIG. 1 showing thetethered connection between the float assembly and the drill mine;

FIG. 3 is a side elevation view in section of the recovery cable storagecompartment as seen along line 33 of FIG. 1;

FIG. 4 is an elevation view of the drill mine and the float device inthe tethered mode, with the drill mine being shown in transversesection; and

FIG. 5 is a side elevation view in section of the timer (shownsymbolically) storage well as seen along line 5-5 of FIG. 1.

DESCRIPTION OF THE PREFERRED EMBODIMENT Referring now to the drawingswherein like reference characters designate identical or correspondingparts throughout the several views, and more particularly to FIG. 1thereof, wherein a drill mine 10 is formed of a substantiallycylindrical metallic case 12 whose exterior dimensions are nearlyidentical to the service mine configuration. A ballast weight 13 may bestrategically positioned within the case 12 to provide the drill minewith similar physical characteristics, such as the center of gravity, toits service mine counterpart. A cylindrical cavity 14 is formed in theforward portion of the drill mine case transverse to the longitudinalaxis thereof. The cylindrical cavity 14 provides a housing for a floatassembly 16 which is releasably fastened thereinby retaining screws 74(FIG. 2) designed to rupture upon application of a large impulse typeforce.

The float assembly 16 includes a housing 17 formed of a suitablemetallic material such, for example, as aluminum, and is of a generallycylindrical shape. A first float compartment 18 and a second cylindricalfloat compartment 20 are defined with the housing 17. The first floatcompartment 18 has positioned therein a substantially cylindricalrecovery line container 24 which itself is divided into upper and lowerportions 26 and 28 by a horizontal separating wall 30. The lower portion28 of the recovery line container 24 provides a housing for a relativelyshort length of heavy tubular braided nylon line 42. The heavy line 42passes through a pair of lugs 44 fixed to the bottom of the floatassembly housing 17 as best seen in FIG. 2. The heavy line 42 furtherpasses through an opening 45 formed in an explosive cutting device 46,which will be described in greater detail hereinafter, permanently fixedto the drill mine case 12. The heavy line 42 is spliced togetherat itsends 47 and forms a continuous loop as may be seen in FIG. 4.

The upper portion 26 of recovery line container 24 houses a substantiallength of nylon recovery line 48. One end of the nylon recovery line 48is fixed to the recovery line container 24 by pin 50 in a reduceddiameter cylindrical portion 27 integral with the upper portion 26thereof. The recovery line 48 passes through an opening (not shown) inthe separating wall 30, through the lower portion 28, and exits from thefloat assembly 16 through a pair of circular openings 52 and 54 formedin the lowermost wall of recovery line container 24 and float assemblyhousing 17, respectively. The other end of recovery line 48 is connectedat 53 to one end of a steel wire rope recovery line 57. The majorportion of the length of the steel rope 57 is housed in a transversecylindrical bore 56 formed behind the cylindrical cavity 14. The bore 56is closed to the external environment by cover member 58 which isfastened by conventional means such, for example, as bolts 60 to theouter drill mine case 12. A gland fitting 62 is provided at the innerportion of cylindrical bore 56 and cooperates with a length of waterresistant tubing 55 to lead in the end portion of steel rope 57 which isfastened to the nylon recovery line 48 and further to prevent leakage ofwater into the mine from the bore 56 which becomes filled with waterupon water entry. The second end of the steel rope 57 is fixed to themine case 12 at lug 49.

The second float compartment 20 contains a conventional buoyant signalfloat 32 which may be of a type such that, upon the rupturing of theouter metallic skin thereof and the consequent entry of seawatertherein, a chemical reaction occurs with a resulting production of vastquantities of smoke and flame. The second float compartment 20 is closedat the top by a cover member 34 having an O-ring 36 positionedtherearound which provides a fluid seal between the external environmentand the inside of the second float compartment. The

lower end of float portion 20 is closed by second cover member 38 whichis affixed to float portion 20 by conventional means, such for example,as by welding.

Cooperating with the second float compartment 20 through the covermember 38 is an explosive fitting 64 which itself is connected by anelectrical cable 66 to a mine fire control system (not shown) of aconventional nature which emits an electrical impulse upon mineactuation, thereby causing initiation of the explosive fitting 64. Theelectric cable 66 also passes through the opening in explosive cuttingdevice 46 nd is of sufficient length to reach the float assembly 16 whenin its tethered mode (see FIG. 4).

The explosive cutting device 46 is of a conventional type and maycomprise a knife edge adapted to move through the opening 45 uponinitiation of an explosive charge. The cutting device is actuated by anexplosive fitting 68 electrically coupled by way of electric cable 70 toa conventional actuation device such, for example, as a mechanical timermechanism 71 (FIG. 5). In lieu of a timer mechanism, other apparatus,such for example, as a remote controlled device 73 may be used toprovide an actuation signal to the explosive fitting 68. The actuationdevice is held in a well 72 substantially adjacent to bore 56 and isadapted to begin its ,7 timing sequence upon water entry of the drillmine. At

the completion of the timing sequence, an electrical impulse isgenerated by the timer mechanism which actuates the explosive fitting68.

In operation, the drill mine 10 is launched in a conventional mannersuch as by an aircraft and a parachute may be employed to retard themines velocity prior to water entrance. After entry, the mine is causedto become horizontally oriented due to its slant nose 80. Immediatelysubsequent to this turn, hydrodynamic forces act upon the drill minecase 12 as the water-air interface of the air pocket created bycavitation moves against the mine case. These impulse forces causeappropriately designed retaining screws 74 (FIG. 2) to rupture, at whichtime the buoyant float assembly 16 exits from the cylindrical cavity 14.The float assembly 16 attains a moored position as best seen in FIG. 4suspended above the drill mine 10 by the heavy line 42. The drill minesubsequently comes to rest on the bottom of the body of water with thefloat device 16 suspended thereabove as described. The mine and floatassembly retain this configuration until a suitable target acquisitionis obtained at which time an impulse from the fire control system istransmitted by electric cable 66 to the explosive fitting 64 resultingin ignition thereof. The ignition of explosive fitting 64 causes thesignal float 32 to be expelled from second float compartment 20. Thecover member 34 has a projection 76 formed thereon which ruptures thewall of the signal float upon its expulsion enabling seawater to entertherein and thereby generate smoke. To enable the float to successfullyexit from the second float compartment 20, a spring 78 provides anoutwardly biased force which causes the float to successfully exit. Itis thus seen that the signal float 32 rises to the surface of the waterunencumbered by any tethering line and a visual signal of mine actuationis accomplished. While the signal float rises to the surface, the floatassembly 16 remains tethered to the drill mine-I0 by the heavy line 42,as may be seen in FIG. 4. After a predetermined time, the timermechanism housed in well 72 causes the explosive fitting 68 to beinitiated by sending an electrical signal through cable 70. Theinitiation of this explosive device causes the cutting device 46 tosever the heavy line 42 and the electric cable 66 thereby allowing thefloat assembly 16 to rise to the surface, while paying out the nylonrecovery line 48 between the float assembly 16 and the drill mine 10.The float assembly is recovered by a recovery vessel and the nylonrecovery line 48 is used to withdraw the wire rope 57 from thecylindrical housing 56. The wire rope 54 is fixedly attached to thedrill mine case at lug 49 and is used to lift the drill mine from thebottom.

Obviously, numerous modifications and variations of the resent inventionare possible in light of the above teachings. It is therefore to beunderstood that within the scope of the appended claims the inventionmay be practiced otherwise than as specifically described herein.

What is claimed as new and desired to be secured by Letters Patent ofthe United States is:

l. A recoverable drill mine which simulates the operational and physicalcharacteristics of a service mine counterpart comprising:

a mine case adapted to be launched from suitable launching means havinga substantially identical shape to said service mine including a firstcavity formed therein;

a second cavity formed in said mine case;

a first recovery line housed in said second cavity having one end fixedto said case;

a positively buoyant float assembly housed in a first position in saidfirst cavity having a first comparb ment and a second compartmentdefined therein, said float assembly adapted to attain a second positionupon said launching outside of said first cavifirst means for flexiblyconnecting said float assembly to said mine case, housed in said firstcompartment;

second means housed in said first compartment for flexibly connectingsaid float assembly to said first recovery line;

a fire control system positioned in said casing and responsive to theinfluence of a mine actuating source to produce a first electricalsignal;

a positively buoyant signal flare positioned within said secondcompartment;

means electrically connected to said fire control system for expellingsaid signal flare from said second compartment in response to said firstelectrical signal;

means for severing said first flexible connecting means in response to apredetermined second electrical signal; and

means for generating said second predetermined signal.

2. A drill mine as recited in claim 1 wherein said means for severingthe flexible connection between said float assembly and said mine casealso severs the electrical connection between said flare expulsion meansand said mine casing and includes an electroresponsive explosive cuttingmember.

3. A drill mine as recited in claim 2 wherein said means for generatingsaid predetermined second electrical signa includes a timing mechanismadapted to begin a timing sequence upon water entry and continue withsaid timing sequence for a predetermined length of time thereafter,whereupon said predetermined second signal is generated.

4. A drill mine as recited in claim 2 wherein said means for generatingsaid second predetermined signal includes signal generating meansresponsive to remote actuation from an external point.

5. A drill mine as recited in claim 3 wherein said first recovery lineincludes steel wire rope.

1. A recoverable drill mine which simulates the operational and physicalcharacteristics of a service mine counterpart comprising: a mine caseadapted to be launched from suitable laUnching means having asubstantially identical shape to said service mine including a firstcavity formed therein; a second cavity formed in said mine case; a firstrecovery line housed in said second cavity having one end fixed to saidcase; a positively buoyant float assembly housed in a first position insaid first cavity having a first compartment and a second compartmentdefined therein, said float assembly adapted to attain a second positionupon said launching outside of said first cavity; first means forflexibly connecting said float assembly to said mine case, housed insaid first compartment; second means housed in said first compartmentfor flexibly connecting said float assembly to said first recovery line;a fire control system positioned in said casing and responsive to theinfluence of a mine actuating source to produce a first electricalsignal; a positively buoyant signal flare positioned within said secondcompartment; means electrically connected to said fire control systemfor expelling said signal flare from said second compartment in responseto said first electrical signal; means for severing said first flexibleconnecting means in response to a predetermined second electricalsignal; and means for generating said second predetermined signal.
 2. Adrill mine as recited in claim 1 wherein said means for severing theflexible connection between said float assembly and said mine case alsosevers the electrical connection between said flare expulsion means andsaid mine casing and includes an electroresponsive explosive cuttingmember.
 3. A drill mine as recited in claim 2 wherein said means forgenerating said predetermined second electrical signal includes a timingmechanism adapted to begin a timing sequence upon water entry andcontinue with said timing sequence for a predetermined length of timethereafter, whereupon said predetermined second signal is generated. 4.A drill mine as recited in claim 2 wherein said means for generatingsaid second predetermined signal includes signal generating meansresponsive to remote actuation from an external point.
 5. A drill mineas recited in claim 3 wherein said first recovery line includes steelwire rope.